Treating ferrous sheets and plates



and similar ferrous metal materials which Patented Dec. 27, 1932 UNITED STATES PATENT OFFICE JOSHUA C. WHETZEL, PITTSBURGH, PENNSYLVANIA, ASSIGNOR 'I'O AMERICAN SHEET AND TIN PLATE COMPANY, A CORPORATION OF NEW JERSEY TREATING FERROUS SHEETS AND PLATES No Drawing.

This invention relates to the manufacture of rolled sheets and plates such as tin plate 7 after being rolled, are pickled and then washed, and after beingv formed into a pile are later subjected to a box annealing operation preparatory to further finishing opera tions.

A most tedious and troublesome operation in the manufacture of such materials, and particularly tin plate, has been the separation of the 'hot rolled sheets or plates in an annealed pile after the first box annealing operation. This separation, known as opening, is essential because the pile of sheets or plates have become welded together or adherent in varying degrees while undergoing the heat treatment to which the piles are subjected in such annealing operations. The same difficulties are encountered but to a lesser extent in box annealing cold rolled materials. I

After the annealing operation it is necessary for each sheet to be freed from any temporary union with the others of the pile so as to be ready for subsequent processing or use. While all of the sheets or plates inan annealing charge are not usually stuck together in the manner indicated, such condi-' tion is present to a very considerable extent in practically'every annealed pile of hot rolled material and to a degree in annealed piles of cold rolled material. The result is that the slow, laborious and costly process of manually opening a pile of annealed materials has been an unescapable feature of the mill routine.

The primary object of this invention is the provision of improved means whereby the objectionable weldingof the sheets and plates ordinarily present after the box annealing operation is prevented or, to a large extent, overcome, and the labor necessary in opening the materials in readiness for cold rolling and further treatment is reduced to a minimum; likewise, the reduction in and preven- 'tion of rust formation and substantial elimination of the de'structivestaining of the surfaces of the sheets or plates generally present Application filed September 25, 1931. Serial No. 565,205.

in the methods used heretofore are effected in a simple, rapid and economical manner.

Still further objects of the invention will be made apparent hereinafter in the detailed description and appended claims.

In the practice of the improved'method the sheets or plates, after the removal of the scale and prior to annealing, are treated by dipping them in a suitable aqueous mixture or chemical solution, preferably a solution or aqueous mixture of a manganese compound such as a solution or aqueous mixture of salts of the oxy acids of manganese or oxygen compounds of manganese dioxide. More specifically, I have found that very good results can be had with a solution or aqueous mixture of dioxid.

With existing tin mill equipment it is possible to provide for the manganese compound treatment by adding the chemical in the proper proportions to the rinse or wash tank at the pi'ckler. A concentration of approxipermanganates OI manganese mately 0.05 per cent. of permanganates or manganese dioxid in the wash water has been found suflicient to accomplish the desired results. Thus, the sheets or plates, as soon as the oxid or scale has been removed by the action of the pickling operation, are immersed, rinsed and treated in a dilute aqueous solution or mixture of the permanganates or manganese dioxid, after which they are inspected in the usual manner and arranged in piles for the black annealing operation.

A more economical and effective method is to provide an additional dipping tank in which the sheets or plates to be treated are immersed in the solution or aqueous mixture after having been rinsed with water in the wash tank. a

Whatever portion of the solution or mixture adheres to the sheets or plates as they are formed into piles on the charging stands is usually allowed to remain onthe surfaces.

It has een found that this treatment practically eliminates troublesome sticking or welding of the sheets or plates in the subsequent. annealing process; that better annealing is obtained; that the annealing temperature can be raised to at least 100 degrees Fahrenheit above that heretofore generally used; that the opening operation is greatly facilitated and that the spoilage of many sheets or plates in the opening operation is avoided. A reduction of approximately per cent. in the cost of opening is thus effected.

Another apparent advantage of the above treatment is a material reduction in the amount of destructive staining on the surfaces of the materials which heretofore has contributed to the production of defective tin coatings.

The broad idea underlying this invention is in that the presence of a separating or reacting medium, extremely thin, and particularly a substance which in itself will militate against welding or sticking of the rolled materials,-will be beneficial.

While the fundamental concept lies in the use of a separating medium between the sheets in the box annealing operation, the important feature was to find the materials that would be effective and at the same time would not, by their presence, interfere with subse uent operations.

In esignating a concentration of 0.05 per cent. permanganates or manganese dioxid as satisfactory I have given this figure only as being representative of the approximate minimum desirable in one particular embodiment of the invention.

Higher concentrations may-be maintained and the manner of application of the solution or aqueous mixture may be modified so that it will fit into any procedure of rolling ferrous metal plates and the like. Concentrations as low as 0.001 per cent. and as high as 0.2 per cent. have been found to give satisfactory results.

The advantages of my invention will be apparent to those skilled in the art. The materlals used in forming the aqueous mixture with which the sheets and plates are treated are not limited to those specifically mentioned therein and other changes may be made within the scope of the invention, as defined by the appended claims.

I claim:

1. The method of preventing sticking in box annealing sheets and plates which conacids of manganese or oxygen compounds of manganese dioxid and piling the treated materials and then box annealing the pile.

3. The method of preventing sticking in box annealing sheets and plates which consists in chemically treating the rolled and pickled sheets and plates by immersion in an aqueous mixture of a manganese compound of a concentration of from .001 to 0.2 percent. characterized by being salts of the oxy acids of manganese or oxy en compounds of manganese dioxid, piling the treated materials and then box annealmg the pile.

4. The method of preventing sticking in boxannealing sheets and plates which consists in chemically treatin the rolled and pickled sheets and plates iy immersion in an aqueous mixture of manganese dioxid of a concentration of .001 to 0.2 per cent., piling the treated materials and then box annealing the pile.

5. The method of preventing sticking in box annealing sheets and plates which consists in chemicall treating the rolled and pickled sheets and pi ates by immersion in an aqueous mixture of manganese dioxid of a concentration of approximately .05 per cent., piling the treated materials and then box annealing the pile.

In testimony whereof, I have hereunto set' In hand.

y JOSHUA C. WHETZEL;

sists in chemically treating the rolled and pickled sheets and plates by immersion in water containin a manganese compound characterized by eing salts of the oxy acids of manganese or oxygen compounds of manganese dioxid, piling the treated materials and then box annealing the pile.

- 2. The method of preventing sticking in box annealing sheets and plates which con- .sists in chemically treating the rolled and pickled sheets and plates by immersion in an a ueous mixture 0 a manganese compound 0 a concentration of ap roximately- .05 per cent. characterized by ing salts of oxy 

